feat: add bounded nightly brain digest

[mrubens]

What changed

• replace per-page dream reflection and pattern fan-out with one bounded nightly digest
• search only the effective-date window since the last successful run
• require citations to eligible primary pages and reject out-of-window sources
• store one digest at daily/digests/YYYY-MM-DD
• keep gbrain autopilot maintenance for embedding and index upkeep
• document the new nightly behavior

Why

The generic reflection pipeline made hundreds of model calls while producing broad, low-value output. A single operational digest is cheaper, easier to inspect, and better aligned with the useful nightly synthesis we want.

Validation

• focused BullMQ test suite (10 tests)
• BullMQ typecheck
• changed-file ESLint
• deployment artifact validation
• pre-push oxlint, fast typecheck, residual lint, and knip checks

[roomote-community]

1 issue outstanding. See task

• apps/bullmq/src/scheduled-jobs/brain-maintenance.ts:238 The digest's effective-date source filter is not enforced.
• apps/bullmq/src/scheduled-jobs/brain-maintenance.ts:278 Concurrent ingestion can be permanently skipped by the digest watermark.
• apps/bullmq/src/scheduled-jobs/brain-maintenance.ts:266 Timestamp boundaries skip date-only source pages.

_{Reviewed 004db7b}

[roomote-community]

search does not accept since or until in the pinned gbrain MCP contract, so these arguments are silently ignored. The downstream synthesize verb also uses its window only in its prompt, not its gather query. As a result, this candidate set can contain historical pages, and eligibleSlugs will accept citations outside the intended effective-date window. Use retrieval that actually filters by effective date, then validate the eligible pages before accepting citations.

[roomote-community]

Switching to query makes the retrieval filter real, but the new 06:00 timestamp bounds still drop date-only source pages. Roomote writes task pages as date: YYYY-MM-DD, which gbrain stores at midnight; its since filter is strict. On the Aug 17 pass, since=2026-08-16T06:00:00Z excludes every page effective-dated 2026-08-16, including work completed later that day, and the next watermark never revisits it. Use bounds compatible with date-granular effective dates (or persist and query a timestamp-granular source date), with a regression test for this case.